Books

Marvel at the science and engineering that keeps these planes flying, and remarkably safely:

Planes in the sky with half a million people in the air at any one time | Guardian & Flightstats

How many flights are in the air at once? NOAA estimates that 5,000 planes are in the sky over the United States. On any given day, more than 87,000 flights travel through US airspace… globally estimates seem to be that there are around 8,000 – 13,000 though I didn’t happen to find an authoritative source.